Quick, who introduced the first automatic hardtops for convertibles? If you're thinking Mercedes-Benz, you're onto something. If you guessed the SLK Roadster, you're right.

The latest evolution of the model--the 2012 Mercedes-Benz SLK Roadster--is just arriving at U.S. dealerships.

It's got a few new features. The optional Magic Sky Control roof (yes, that's the real name) tints the top of the car to reduce light in the cabin. It works by using the same technology as automatic dimming mirrors--a matrix polymer film inserted between two panes of roof glass holds nano particles that line up perfectly when electrical current is applied but disperse when the current is switched off, which clouds the roof panel. The roof retracts in 20 seconds, two seconds faster than its predecessor and five seconds faster than the original SLK roof that debuted in 1996.

The SLK350.

Another feature: the optional plexiglass wind deflectors mounted on each rollbar can be adjusted independently to help dampen buffeting. That's in addition to the seatback air scarf heaters that blow warm air down your neck and adjust pressure according to driving speed. It may not sound like much, but they make a big difference on days that are borderline too-cold to drive with the top down.

The car has a wide front grille and long front hood, with the tiny rear Merc coupes always seem to have these days. It has short front- and rear-wheel overhangs and flared fenders near the standard halogen (optional bi-xenon) headlights, with LED daytime running lights integrated in the front bumper.

Inside the SLK350.

Under the hood, the new SLK350 model debuts a 3.5-liter, direct-injection V6 engine that gets 302 horsepower and 273 lb.-ft. of torque. Its 0 to 60 mph time is 5.4 seconds, with a top speed of 155 mph. That sits well with competitors like the Porsche Boxster and BMW Z4, which are slightly less powerful and more affordable in their base models ($48,100 Porsche Boxster and $47,450 BMW Z4; both 255 hp and 0-60 mph in 5.6 seconds) but have as much power and more speed in the higher variants.

Mercedes estimates that the 7-speed automatic SLK350 will get 20 mpg in the city and 29 mpg on the highway. (Next year look for a 201-hp SLK250 with a turbocharged four-cylinder engine, which will have slightly better efficiency of around 23 mpg city/31mpg highway.)